Simplify the following expression: $p = \dfrac{r}{2} + \dfrac{r}{8}$
In order to add expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $2$ and $8$ $\lcm(2, 8) = 8$ $ p = \dfrac{4}{4} \cdot \dfrac{r}{2} + \dfrac{1}{1} \cdot \dfrac{r}{8} $ $p = \dfrac{4r}{8} + \dfrac{r}{8}$ $p = \dfrac{4r +r}{8}$ $p = \dfrac{5r}{8}$